Haunted
by Shwatsonlocked
Summary: Sherlock and John attend a Halloween party for the Met, where an uninvited guest with some unfinished business drops in. They return to the flat, but they aren't alone. Written for the October contest at fuckyeahjohnlockfanfic.


**Title:** Haunted

**Author: **Shwatsonlocked

**Pairing|Characters:** Sherlock Holmes/John Watson

**Length:** 3,230 words

**Genre:** fluff, romance, horror

**Warnings**: Established relationship, spooky

**Rating: **M

**Disclaimer:** Moffat, Gatiss, and Conan-Doyle own the characters, I'm just making them dance to my tune.

**Summary: **Sherlock and John attend a Halloween party for the Met, where an uninvited guest with some unfinished business drops in.

* * *

Paranormal. Things that lie beyond the realm of scientific explanation.

They say that you only start to believe while you're experiencing something you can't explain. A shadow in the doorway where no one stands, the feeling of someone, some_thing_, watching you while you sleep. Objects that have moved from where you left them. What they don't say, is that it changes you, even if you don't feel any different. When the lights flicker or a stair squeaks in the otherwise empty house, it leaves you wondering...are we really alone?

John Watson had never been a believer in the supernatural, in ghosts or vampires, witches or demons. He'd seen demons in enemy soldiers in Afghanistan, ghosts in the boys fresh from the warzone and that was enough really. Three years ago, he saw the devil in Jim Moriarty, and when he'd found out that the devil was dead, he thought that would be the end of it.

Sherlock Holmes believed in mermaids until he was seven. He never believed in ghosts or werewolves, in angels or yetis, but he believed in mermaids. When he was nine, he followed the local swim competitions, envisioning the swimmers as merpeople and when one of them drowned in the pool, he was drawn to the puzzle of how it happened. Carl Powers hadn't been a merman, but he never would have drowned the way they said. Sherlock tried to convince the police about the missing shoes, but who would listen to a nine year old.

Now though, now they both believed.

* * *

_31 October 2015_

Sherlock was stretched out on the sofa of 221B Baker Street when John came back from picking up their costumes. Sherlock had been trying to back out of attending the Met's Halloween party for days, ever since they'd been invited.

"Can't go to the party, John. Delicate experiment in the sink." Sherlock said, long fingers steepled under his chin.

Evidently, he wasn't done trying to talk John into not going. John lay their costumes on his armchair before facing the consulting five-year-old. "No there isn't. You're only saying that because _you_ are still trying to wriggle out of going tonight," he said, crossing his arms.

Sherlock huffed and sat up. "Why is it so important that we go? It's going to be _boring_."

"We're going because Greg invited us and he's the one who let us back into crime scenes. He also happens to be your friend, yes _friend_, Sherlock, don't look at me like that," John said with mild exasperation. "Besides, you can just deduce why people chose their costumes."

The detective gave a slight noise of agreement before shifting his gaze to examine the outfits John had chosen. Sherlock narrowed his eyes and seeing the gleam in the silvery gaze, the one he got when John forced him to eat during a long case, John braced himself for histrionics. It was risky, picking the costume he had and he really shouldn't have been surprised at how fast Sherlock figured it out. He probably deduced whose was whose from the length of the sleeves or the way he draped them over the chair.

"I'm not wearing that," Sherlock said, his dressing gown clad shoulders tensed, as though the yards of fabric were a threat, ready to jump from the chair and attack. The mental image made John's mouth twitch in amusement.

"Yes you are."

"Mycroft told you. He was lying."

"No he wasn't, now shut up and get dressed." John said with a smirk, tossing the pirate shirt at his partner and grabbed his own costume.

* * *

Sherlock was attaching the plastic sword to his belt when John walked back into their room. Their room. Sherlock had only been back for a few months but John had come to terms with his feelings for the genius in the three years he was 'dead'. A discussion on what happened, how it was more than a bit not good, and a solid punch to the sharp cheekbones led to John saying "Sod it" and kissing his best friend.

As John took in the sight of Sherlock dressed as a pirate, he realised that it might not have been a wise decision. He shifted his stance to be more comfortable with his growing erection as his partner turned around, the purple shirt laced loosely to expose the pale skin underneath.

"About ready?" he asked, tongue darting out to wet his lower lip.

Sherlock's eyes flicked up and down John, studying his costume. He could see Sherlock's pupils dilating but his partner turned back toward the bed, picking up the black captain's coat. Apparently Sherlock's military kink extended to costumes. John could work with that.

"Eighteenth century British Naval officer to go with the pirate. Is this some sort of couples costume, John?"

"Possibly. We are a couple, and we're dressed for Halloween. Don't act like you don't like it. I may not be the genius detective, but I saw the way you looked at me just now," he said, walking so he was standing behind his taller lover. He heard the sharp intake of breath and smiled. It wasn't time to leave yet, the sun only beginning to set, so John grabbed hold of Sherlock's wrists and tugged his body closer. The costume coat fell to the floor.

"I seem to have captured a pirate. Wonder what I should do with it?"

"John, you're being ridiculous. I am a consulting detective not a-"

John flipped Sherlock around and crushed their lips together, fingers tangled in curly hair. He nipped at the plump lip and Sherlock released a low groan. John pulled back.

"Still think it's ridiculous?"

Sherlock shook his head, swallowing thickly. The way the adam's apple bobbed was almost obscene. John leaned forward, attaching his lips to the smooth column of Sherlock's throat. He felt the vibration of the vocal chords as Sherlock hmm'd in pleasure. The sound sent a jolt straight to his cock and it twitched against Sherlock's thigh.

_Thunk_

John was pushed away. Confused, he turned to see Sherlock staring down the hall to the living room. "Sherlock, wh-"

"Quiet, John."

John bowed his head, taking a deep breath and willed his erection away.

Sherlock had walked out of their room and John followed, wondering what had distracted his partner. He was holding the skull, studying it with a look of confusion.

"Did you drop Billy?" he asked, not glancing up.

John blinked, surprised. Five years later and he finds out the skull had a name. "Billy? You named the skull _Billy_? Right, nevermind. No, I haven't touched the...Billy. Why?"

"He's obtained a crack along the sphenoid and temporal bones that wasn't there before. I thought I heard someone in the flat but there are no signs of entrance or exit."

"So he got the crack sitting on the mantle?"

"No, he was on the floor. Nothing else seems to have moved." Sherlock frowned but placed the skull back.

"Odd," he said, glancing out the window. It was getting dark. "We should leave; go fetch your coat." John crossed over to the door to wait. When Sherlock walked out of the bedroom, there was a flash of something flitting across the doorway. John stared in shock.

Sherlock shot him a questioning look but he shook his head and shut the door behind them. Just a trick of the mind, John. Just a trick of the mind.

* * *

"Glad to see you could make it, Sherlock, John." Greg greeted them at the door.

John looked at the brown hat and sandy coloured jacket the Inspector wore and took a guess. "Indiana Jones?"

"Big game hunter, actually. Had an ancestor who hunted in South Africa, thought it'd be new,"he said, grinning.

Sherlock spoke from beside him. "I see Anderson decided not to wear a costume."

Said forensic officer must have been in earshot, because the next thing John heard was a noise of protest and angry footsteps. Anderson was wearing what looked like village peasant clothes. "I did too. I'm a-"

"Idiot as usual, yes, well done." Sherlock was smirking. Sensing a fight, John smiled apologetically and led the detective away to get drinks.

"You can let go of my arm, John, I am perfectly capable of walking to the drinks table."

John scoffed. "I'm not so sure. You'd probably get into a brawl halfway over here."

"I do not _brawl_," Sherlock said, drawling the last word with distaste.

"Fisticuffs. Scrap. Fight. Use whatever word you want, but most of the people here would love an excuse to knock you down a peg and lock you up."

Sherlock's response was cut off as the lights flickered and died, leaving everyone in complete black. Even the exit signs had extinguished.

Greg's voice rang out from across the dark, calling for patience until the backup generators started. John could feel hair on the back of his neck stand up, feeling like something was breathing down his neck, with intent to hurt him. It was terrifying. He grasped blindly for Sherlock's hand, finding it after a few seconds.

_BANG!_

Women and men screamed in surprise. John could feel Sherlock jump at the sudden noise and squeezed his hand reassuringly. There was a whooshing sound as the air started and then the lights were back.

John cleared his throat, glancing around the room. "What was that loud bang?"

"Look at the doors." Sherlock's voice was eerily calm.

"What about the doors?"

"They've all hit the wall hard enough to leave cracks."

"You're saying that the doors banged open during the blackout? All at the same time."

"Technically you're the one who said it. Everyone appears to be leaving," Sherlock said, pulling John after him toward the door. Evidently they were leaving as well. They'd call Lestrade tomorrow and see what the cause of the blackout was.

* * *

They finally caught a cab back to flat after thirty minutes of terrified Yarders jumping into every empty one that drove past. Sherlock was back in his dressing gown, standing by the window, plucking the strings on his violin.

"Did you hear the woman talking on our way out, about being scratched while the lights were gone?" John asked from his armchair before finishing his cup of tea.

No answer. John hadn't really expected one.

"Well, I'm knackered. Join me when you're done?" There was an upward trill that John took to mean yes. He dropped his cup in the sink and headed to the bedroom to turn in.

* * *

A sharp pain in his leg woke him up but the frantic wheezing next to him had him completely alert. John reached over, trying to knock whomever was strangling Sherlock away, but felt nothing there. The breathing evened out, and John felt his racing heart slow down.

"Sherlock, what was that? You okay?" he asked, turning on the lamp.

"Mo-moriarty. Not dead. Moriarty...was strangling me," Sherlock gasped out.

John turned back around so quickly, he almost gave himself whiplash. "That's not possible. Wait, let me see your neck." John paused to lean closer and get a proper look. "I don't understand. Nothing was there. I reached over and nothing was there. So how..." he trailed off, utterly confused.

"How what? What do you see, John? Tell me!"

"You've got bruising, manual strangulation. They look like someone's fingertips were pressed against the sides of your throat. Someone was strangling you but _nothing was there_."

"That's impossible. You must have missed them in the dark. They weighed about 68kg, hands were about your size. Were you trying to kill me, John?"

"Not amused, Sherlock." John rubbed a hand over his face and sighed. His internal clock told him it was around 5 in the morning. "Come on, let's get an ice pack on those marks."

"I'll stay here."

"Oh no, you're not staying in here alone. The ghost killer might come back while I'm in the kitchen."

Sherlock pouted but got up anyway, walking into the living room to lay on the sofa. John grabbed a flannel and a few of the ice chips he insisted on having for medical emergencies and quickly moved back into the living area.

"Budge up, you selfish bugger. You can't have all the sofa." he teased, sitting where Sherlock made room...by lifting his head. John smiled fondly and held the flannel to the neck stretched out on his lap. Sherlock had his eyes closed and hands steepled under his chin, apparently thinking about tonights events. John was entranced watching him, the way his eyelids flickered and brows furrowing together, deep in thought. The floor lamp began to flicker and in his peripheral, John could see the kitchen lights doing the same.

"Sherlock, the lights. They're flickering." Sherlock's eyes shot open and they were plunged into darkness again, like at the party. He felt Sherlock sit up next to him and grabbed his wrist so John knew where he was. There was a faint scratching, almost peeling noise to their left and John shuddered.

"Show yourself." Sherlock's voice was steady and had John not been grabbing onto his slightly shaking palm, he would have believed him to not be afraid at all. John was, though he also felt the familiar rush of adrenaline coursing through him. Something rolled into their feet. Picking it up, he could feel it was one of the apples from their fruit bowl. He passed it to Sherlock.

"I owe you," the man next to him murmured.

"Owe me? Owe me what?"

"No. It's carved into the apple, feel." Sherlock grabbed John's hand, guiding his fingers along the carving.

A voice that was not Sherlock or John spoke from the direction of the peeling sound. "Very good."

"No. It's impossible. Ghosts don't exist."

"I beg to differ. Tonight's been fun, teasing you with my presence. I bet you're the only one who saw the message at the party. You didn't complete my story, Sherlock, and we're almost out of time."

"You lost, Jim. Your little organization is gone and so are you."

"We'll see about that," the ghost of Moriarty said before slamming into John, knocking him to the floor.

* * *

The lights came back on and Sherlock looked over to see John sprawled on the floor. He felt his stomach clench and bent down to check for a pulse. His body temperature was cooler than usual, but his heart rate was normal. He gave a small sigh of relief before standing to investigate the chair 'Moriarty' had occupied. There was no imprint in the seat, yet the apple peels littered the floor directly beneath the chair. The knife was stabbed into another apple in the bowl. For the first time since seeing the Hound in Baskerville, Sherlock was unable to explain what happened. He'd seen the small "Get Sherlock" carved among the wall cracks at the Met's party but what had Moriarty, if that was Moriarty, meant by them almost being out of time?

Sherlock began looking for his nicotine patches. He needed to think. This was a scientific impossibility so how-

The breath was knocked from his lungs as John barreled into him, sending them crashing to the floor.

"John! What are you doing?" he gasped out, barely moving his skull out of the way in time to dodge the punch his partner threw. Sherlock grabbed at John's shoulder and managed to push him off. He scrambled to stand and John did the same.

"Completing the story."

Sherlock narrowed his eyes. "You're Moriarty." How did he take over John's body?

"Good, you got that too. "

"How are you doing that?"

"If you're worried about your pet, he's fine. For now, at least. He'll be a bit torn up after he kills you, unless you kill him. You see, Sherlock, that's the only way I'll be leaving."

He was lying, he had to be. The comment about almost being out of time must mean there's a time limit to how long he can stay in a living body. But what's the limit? How long can he fight John off without either of them dying?

Moriarty in John's body pulled the knife from the apple, brandishing it in front of him. "I never liked getting my hands dirty, but I'll make an exception in your case."

"Those aren't your hands," Sherlock said, bracing himself. Moriarty had no time to lose and would attack first.

The answering smirk on John's face looked wrong, utterly wrong. It twisted his face into something inhuman. Moriarty lunged forward, slashing the knife downward, Sherlock jumping back to avoid it. He thrust the knife forward and Sherlock caught the arm, twisting it behind his back. Possessed John was stronger than usual and Sherlock was flung off and into the wall.

He winced slightly as he was dragged out to the middle of the floor. Moriarty straddled him, the cold metal of the knife pressing against his throat.

"I was wrong before. This is sexier. Your skull cracking into pieces wasn't going to be as beautiful as your throat gaping open, the blood pouring out, pooling around us. Poor Johnny will be covered in your blood."

Odds of their survival were decreasing as seconds passed. He needed to keep Moriarty talking. "I was wrong."

Moriarty arched John's brow. "Wrong about what?"

"You aren't a ghost at all. You're the devil," he said, hoping it would distract the ghost occupying John's body.

"You're trying to flatter me. It won't work."

"Most people wouldn't take that as flattery."

The grip on the knife slackened and Sherlock brought his own arm up to keep the knife away from his throat. Out of the corner of his eye, Sherlock could see the sun beginning to rise and it clicked, like the last piece of the puzzle finding its spot. Sunrise was the deadline.

Moriarty must have noticed the lightening sky, because the pressure on his arm increased and a feral look took over John's face. He was desperate now. The knife was dangerously close to slitting him open, he could feel the sting of a small cut and a bead of blood trickling down his neck. The sun rose higher and higher until the window was streaming with light. John's body arched and a dark mist shot out of his pores, vaporising in the light before John collapsed heavily onto a relieved Sherlock.

* * *

John came to while they were still laying on the floor, Sherlock clinging to him like a child clings to a favourite stuffed animal. He'd been horrifyingly aware of the fight, unable to do anything until Moriarty had been distracted.

"You're alright. We're alright," he said soothingly. It was over.

"I love you," Sherlock mumbled into his shoulder. John was surprised. They'd never said the words, never needed to. It was implied. Having a relationship with someone like Sherlock Holmes was never going to be like any relationship John had ever had. Which was more than okay, because he wanted Sherlock, loved him.

"I love you, too." It was nice though, to say it. To hear it out loud instead of just in his head. "We're okay," he repeated. He wasn't sure what else to say after what happened. What are you supposed to do after being possessed?

When Sherlock's phone beeped, John had his answer. You go to a crime scene.

* * *

A/N: Written for the fuckyeahjohnlockfanfic October contest. Hope you enjoyed and Happy Halloween!


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